#066FDF
Closest named color: Cerulean Blue (#056EEE). oklch(55.6% 0.19 256.4), rgb(6, 111, 223).
Aa
White text reads best on this color (4.83:1).
About this color
#066FDF is a medium-dark, vivid blue. In OKLCH its lightness is 56%, its chroma 0.190 and its hue 256°. Its hue sits on the cool side of the wheel. The nearest named color is Cerulean Blue (#056EEE), ΔE 0.023 away. White text reads best on it, at 4.83:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | vivid (0.190) |
| Temperature | cool |
| Nearest name | Cerulean Blue (#056EEE) |
| Black text | 4.34:1 |
| White text | 4.83:1 |
Values
| HEX | #066FDF |
| RGB | rgb(6, 111, 223) |
| HSL | hsl(211, 95%, 45%) |
| OKLCH | oklch(55.6% 0.19 256.4) |
Contrast
WCAG 2 contrast ratios are the conformance target: AA needs 4.5:1 for body text and 3:1 for large text, AAA needs 7:1. APCA Lc values are supplementary guidance from the WCAG 3 drafts.
| Pair | WCAG 2 | Result | APCA | APCA guidance |
|---|---|---|---|---|
| White text on #066FDF | 4.83:1 | AA | Lc -78.2 | Fine for body text |
| Black text on #066FDF | 4.34:1 | AA large text | Lc 31.4 | Non-text elements, placeholder text |
| #066FDF text on white | 4.83:1 | AA | Lc 72.7 | Content text, not long reading |
| #066FDF text on black | 4.34:1 | AA large text | Lc -29.0 | Dividers and decoration only |
Tints and shades
A 50–950 scale built in OKLCH: the hue is held, lightness follows a Tailwind v4-like curve, and every step is kept inside the sRGB gamut. This color sits at step 600.
-
Step 50
50
#F1F6FD
oklch(97.1% 0.011 256.7)
-
Step 100
100
#DFEBFB
oklch(93.6% 0.025 255.6)
-
Step 200
200
#C5DBF9
oklch(88.5% 0.048 256.2)
-
Step 300
300
#9DC3F8
oklch(80.9% 0.086 256.8)
-
Step 400
400
#65A2F4
oklch(70.6% 0.137 256.2)
-
Step 500
500
#3788F0
oklch(63.1% 0.175 256.3)
-
Step 600
600 (this color)
#066FDF
oklch(55.6% 0.19 256.4)
-
Step 700
700
#005DBE
oklch(49.2% 0.17 256.3)
-
Step 800
800
#024C9D
oklch(42.8% 0.147 256.4)
-
Step 900
900
#10407C
oklch(37.6% 0.114 256.4)
-
Step 950
950
#0B2649
oklch(27% 0.073 256.3)
#066FDF with color blindness
Simulated with the Machado et al. (2009) model. ΔE is how far the color moves: below about 0.02 you would not notice a change.
| Vision | Seen as | Shift (ΔE) |
|---|---|---|
| Protanopia (no red cones) | #237BE3 | 0.035 |
| Deuteranopia (no green cones) | #0069DD | 0.016 |
| Tritanopia (no blue cones) | #008B9C | 0.144 |
| Achromatopsia (no color) | #727272 | 0.190 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #066FDF
#066FDF
oklch(55.6% 0.19 256.4)
- #996800
#996800
oklch(55.5% 0.116 76.4)
Analogous
Neighbouring hues, 30° either side.
Split complementary
The two hues beside the complement (150° and 210°).
Triadic
Three hues spaced 120° apart.
Palettes with this color
Curated palettes that contain a color within ΔE 0.04 (OKLab) of #066FDF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cerulean Blue #056EEE ΔE 0.023
- Royal Blue #4169E1 ΔE 0.033
- Azul #1D5DEC ΔE 0.048
- Neon Blue #4361EE ΔE 0.050
- Bright Blue #0165FC ΔE 0.051
- Clear Blue #247AFD ΔE 0.055
- Windows Blue #3778BF ΔE 0.063
- Warm Blue #4B57DB ΔE 0.065
Use #066FDF in your product
Turn it into light and dark UI roles checked for contrast, then export to Tailwind v4, shadcn/ui, CSS or design tokens.